Vehicle axle having electric drive motors, an electrohydraulic brake and additional modules such as a transmission, torque vectoring and a parking brake

ABSTRACT

A vehicle axle may include hydraulically operating wheel brakes and/or additional hydraulic loads, such as clutch plate cylinders. The vehicle axle may include at least one pressure supply device, driven by an electric-motor drive, to control pressure in the wheel brakes; at least one control and regulating device; a valve assembly having values for setting wheel-specific brake pressures and/or for disconnecting/connecting the wheel brakes from/to the pressure supply device, and at least one electric drive motor for driving and braking a vehicle wheel or the axle. At least one pressure supply device is used to control the pressure of and/or provide pressure to at least one additional brake unit in the form of an electric parking brake, a hydraulically supported electromechanical brake, an electromechanical brake and/or a force-supporting steering device, a gear actuator and/or transmission actuator, and/or a torque vectoring module.

The present invention relates to a device for an electric axle forelectric vehicles, in particular designed for vehicles in increasingautonomous driving operation

PRIOR ART

The automotive industry is undergoing a disruptive change process. Inaddition to the increasing market penetration of electric vehicles,various stages of automated driving are being passed through, these areinitially: Level 3—highly automated driving—HAD, level 4—fully automateddriving—FAD, and level 5—autonomous driving—AD with each levelincreasing the demands on the braking systems used.

This has driven the development of new braking systems forward. Thereplacement of vacuum brake boosters with electric brake boosters(e-BKV) began in 2005 after initial approaches [ATZ edition 6/11] withthe market launch of what are termed 2-box solutions with electricalslave brake boosters and an additional ESP unit in 2013 [ATZ edition4/18] followed shortly by the first integrated 1-box systems with pedalsimulators in 2017 [Bremsenhandbuch—Chapter 20]. Solutions for level 3(HAD) are currently being developed.

From level 3 (HAD), a redundant pressure supply is mandatory for thefirst time. In addition, a connection between the brake circuits and thereservoir should be avoided as far as possible in the case of openbraking systems, and pedal feel simulators with constant pedalcharacteristics should be used. A redundancy of the ABS function mustalso be provided. This is implemented in what are termed 2-box systemswith electric brake boosters and an ESP/ABS unit according to the priorart according to DE112009005541B3 in such a way that the electric brakebooster (e-BKV) takes over a pressure modulation function in the eventof failure of the ESP unit in order to always ensure high vehicledeceleration. In the first step, what is termed an “ABS select-lowcontrol” was introduced.

From level 4 (FAD), 3-fold redundancies are expected for sufficientsystem availability, e.g., with the pedal sensors with the rule “2 outof 3”. In addition, a pedal simulator is essential because of theincreasing recuperation performance of electric vehicles and a lack ofacceptance of changes in the pedal characteristics because fullyautomatic driving (FAD) can be operated over a longer period of time andthe vehicle driver is not prepared for a change in the pedalcharacteristics when switching to piloted driving. To monitor thepressure supply, a redundant pressure transducer must be provided or analternative diagnostic option must be provided. A redundant ABS functionwith at least individual axle control will also be required and partialredundancies will be introduced. Braking systems with closed brakecircuits in ABS operation have safety advantages.

In level 5 (AD), the pedal position sensor and pedal simulator and theircharacteristics are no longer relevant. In contrast, the remainingcomponents and subsystems will have triple redundancy, with the rule “2out of 3” for sensors, control and regulating units ECU and part-ECU, ormultiple redundancy. In addition, complete redundancy must be providedfor the individual wheel control.

Several new vehicle manufacturers such as Apple, Uber and Waymo areworking on completely autonomous vehicles without a vehicle driver,which in the first expansion stage have a brake pedal with a simplepedal feel simulator unit (level 4 FAD) and in the last expansion stage(level 5 AD) should no longer have a brake pedal. In addition, vehicleswith powerful electric drive motors on both the rear and front axles arebecoming increasingly popular.

In addition to the electrohydraulic braking systems described, theelectromechanical brake (EMB, electromechanical wedge brake) is a knownsolution. The EMB has not caught on in the past due to safety concernsand high costs. The high costs are due in particular to the fact that anelectric motor and a complex electromechanical mechanism are requiredfor each wheel brake. In addition, an EMB has a large number ofelectrical contact points, which are known to be more prone to faultsthan hydraulic lines.

For reasons of cost and reliability, braking systems for the FAD and ADlevels cannot exclusively have EMB or wedge brakes. An EMB is onlysuitable for the rear axle of a vehicle because the rear axle has asmaller share of the braking force and a failure is not viewed ascritically as on the front axle. A hydraulic braking system with controlin the predominantly closed brake circuit via an electrically drivenpiston-cylinder unit is thus preferred.

In DE102005055751B4 and DE102005018649B4, the high-precision pistonpressure control (PPC) is implemented by means of an electrically drivenpiston-cylinder unit having a spindle drive. The pressure is controlledusing a non-linear map, what is termed the pressure-volumecharacteristic, in which the relationship between pressure and pistonposition is evaluated. Alternatively or additionally, the pressure isused by phase current control of the electric motor, the physicalrelationship of proportionality between current to torque and, due to aknown piston area and fixed gear ratio, proportionality between currentand pressure also existing and being used. With these two parameters,the pressure and the pressure change curve can be controlled veryprecisely.

In EP1874602B1 and EP2396202B1 what is termed the multiplex method (MUX)is described, which is particularly suitable for the requirements oflevels 4 and 5 since a closed braking system, as explained later, doesnot have any dormant faults. In addition, a plurality of wheel brakescan be pressurized and depressurized with only one switching valve each,either simultaneously or one after the other. The high dynamic demandson the electric motor are disadvantageous, in particular if all wheelbrakes are controlled by one motor.

This requires a special motor with a double air gap such as is knownfrom EP1759447B1 or a motor with a very low inertia mass.

In WO201614622A2 a special valve circuit of switching valves is alsoimplemented, where the interior of the switching valve is connected tothe associated brake circuit via a hydraulic line and the valve seatcompensation is connected to the associated wheel brake via a hydraulicline. This valve switching is particularly suitable for the MUX methodwith only one switching valve per brake circuit, since in the event of afault the solenoid valve opens due to the pressure in the wheel brakeand thus prevents the pressure from remaining locked in the wheel brake,which leads to undesired vehicle deceleration.

Certain components of braking systems are to be regarded as critical tosafety. These are seals for pistons, solenoid valves and ball screwdrives. Various faults and their effects are listed below:

-   -   Piston: Piston seals can fail, although the leakage may not yet        occur at low pressures, for example, but only at high pressures.        Leakage leads to a failure of the piston function. Pistons are        used in path simulators, pressure supplies and master brake        cylinders (HZ) and can lead to pedal failure or failure of the        pressure supply.    -   Solenoid valves: Dirt particles can settle in the valve seat. If        solenoid valves in an open braking system are connected to the        reservoir, for example, particles can settle when they close and        the connection is not tight. The tightness cannot be diagnosed        when open.    -   Ball screw drive: Ball screw drives wear out over their service        life and can jam, in particular if dirt particles get into the        ball screw drive. This can lead to failure of the pressure        supply.

The requirements for level 3 (HAD), level 4 (FAD) and level 5 (AD)braking systems and for e-vehicles that have increasingly powerfulelectric drive motors on one or more axles can be summarized as follows:

-   -   completely noiseless operation, i.e., no disturbing noises from        units on the bulkhead;    -   even shorter construction than conventional cars due to new        vehicle platform concepts for electric vehicles;    -   brake intervention for individual wheels or axles, even in the        event of complete or partial failure of modules;    -   functional scope ABS, ESP, ASR, recuperation and torque        vectoring with the least possible restriction of performance        even in the event of complete or partial failure of modules;    -   maximum recuperation of the vehicle's kinetic energy through        maximum utilization of the braking power by electric motors;        therefore dynamic and precise control of the hydraulic braking        system as required;    -   use of available braking torques, e.g., from drive motors to        simplify the braking systems or shorten the braking distance;    -   increased safety through redundancy of the systems, signal        transmission and power supply;    -   diagnostic methods for detecting leaks or avoiding dormant        faults;    -   high demands on the control accuracy for further braking        distance reduction, in particular when electric drive motors and        hydraulic braking torques work together;    -   high modularity of the systems, i.e., the use of the same        parts/modules, in particular for the pressure supply; modularity        is driven by a large number of vehicle drive concepts, in        particular in the coexistence of vehicles with internal        combustion engines, hybrid vehicles and pure electric vehicles        (internal combustion engines, hybrid engines, pure electric        vehicles, driverless vehicles).

Now that electric vehicles are increasingly establishing themselves onthe market, electric axle concepts are becoming increasingly popular.There, electric motors are an integral part of one or more axles, andaxle concepts with integrated electric motors are increasingly beingoffered by various suppliers as part of the platforms of electricvehicles. This achieves maximum flexibility in vehicle design andvehicles can implement new vehicle interior concepts because theinternal combustion engine is no longer a length-limiting factor.

In order to further minimize the overall length, it makes sense tointegrate braking systems and clutch actuators into an e-axle and toclear out the bulkhead of the vehicle with fewer actuating elements orno actuating elements in the case of fully autonomous driving

OBJECT OF THE INVENTION

The object of the present invention is to provide a vehicle axle forelectric vehicles with an integrated actuator for braking and vehicledynamics tasks which fulfills the requirements of high availability infully automated driving (FAD) and autonomous driving (AD) and alsocreates the basis for the integration of additional hydraulic actuators,in particular for the steering, transmission actuators and torquevectoring modules.

Achieving the Object

The object of the invention is achieved by a vehicle axle having thefeatures of claim 1. Advantageous designs of the vehicle axle accordingto claim 1 result from the features of the dependent claims.

The invention is advantageously characterized in that redundancyrequirements of fully automated driving (FAD) and autonomous driving(AD) are met and, at the same time, high synergy effects are used in theinteraction of the braking system with electric drive motors of electricvehicles. For example, the energy recovery of kinetic energy by theelectric motor is not limited by the braking system as for example inthe case of slave brake boosters without path simulator according to DE11 2009 005 541 B3, while at the same time the electric motor cancontribute to braking. The vehicle axle according to the invention isadvantageously equipped for FAD with an actuating unit (BE) with a pedalfeel simulator. However, it is also possible to implement the brakingsystem according to the invention for AD without an actuating unit (BE),the braking system then being controlled by a superordinate control.

In the embodiment for level 4 (FAD), an actuating unit withcorresponding redundancies must be provided for autonomous driving. Theactuating unit (BE) optionally has a hydraulic connection to at leastone brake circuit or is used as a pure pedal feel simulator without aconnection to the hydraulics of the braking system, the actuation forcethen being transmitted purely electrically. An electric brake pedal(e-brake pedal) can be designed hydraulically or electromechanically.The aim is to make the actuating unit extremely short so that the lengthadvantages of e-axle concepts can be fully exploited.

In the embodiment for autonomous driving (AD), no actuating unit isprovided, a central control and regulating unit (M-ECU) taking over thecommunication with the actuating units.

For the vehicle axle with wheel-specific redundant brake control, theinvention provides in a basic embodiment that

-   -   the vehicle axle has at least one pressure supply device        (DV1-A1, DV2-A2) with a piston-cylinder unit, the piston of        which is adjusted via a gear, in particular a spindle drive, by        an electric-motor drive (M1) for pressure control in the wheel        brakes (RB1-RB4, H-EMB)    -   the pressure supply unit is filled out redundantly in such a way        that either one pressure supply device is redundantly equipped        with two electronic control and regulating units and in        particular piston-cylinder units with redundant piston seals or        another pressure supply device on the same axle or on another        axle takes over the pressure control;    -   one or a plurality of pressure supply devices, preferably in        addition to the brakes, also control other hydraulic actuators,        in particular clutch and gear actuators, transmission locks,        torque vectoring modules or hydraulic steering actuators, or        form the pressure supply for these or perform the pressure        control;

This design provides at least double-redundancy, at least for thepressure supply and its control, and a plurality of hydraulic actuatorscan be controlled very precisely with only one or fewer, in particulartwo, pressure supply devices. A very inexpensive and also reliablesolution for a plurality of hydraulic actuators (brake, gear actuator,steering) can thus be implemented. In addition, thanks to the veryprecise pressure control based on the basic patents DE102005055751B4 andDE102005018649 B4 for the PPC method, comparable with the quality of apurely electromechanical solution (e.g., electric power steering,electromechanical brake) can be achieved at significantly lower costs.

The vehicle axle is preferably constructed in such a way that allhydraulic components or actuators (brakes, steering, gear actuators,clutches, etc.) with slave electronics and hydraulic control units HCUwith valves and pressure transducers are positioned on the vehicle axleor are sensibly integrated into the units and all modules are controlledvia a superordinate control unit (M-ECU) that is not located on thevehicle axle. Actuating units such as, in particular, the brake pedal onthe bulkhead facing the vehicle interior are also possible. Theactuating units are not required for vehicles of level AD.

The control signals to the various components or actuators of thevehicle axle can preferably be transmitted redundantly and a fast BUSsystem such as Flexray® is preferably used for fast data transmissionwithout delay. Diagnostic processes as well as motor and pressurecontrol are part of the slave ECU modules of the various components.

In an additional development of the basic embodiment according to theinvention for providing an additional redundancy, it is provided that atleast one, in particular each, electronic control and regulating unitcontrols separate windings of the or an electric-motor drive. Thisadvantageously ensures that if a winding system fails, the drive motorcan still be operated with at least half the maximum torque.

The embodiments described above can also be made more reliable if eitherone, in particular redundant, valve assembly is assigned to eachpressure supply device, or one redundant valve assembly is assigned totwo pressure supply devices. The invention understands a redundant valveassembly to be designed in such a way that if one or both control andregulating units of the pressure supply device fail, the solenoid valvesof the pressure supply or the assemblies of the vehicle axle can stillbe operated safely.

If an actuating device is provided, in particular in the form of a brakepedal, it is advantageous if this acts on a piston-cylinder unit andadjusts its piston so that, in the event of a fault, a brake pressurecan be built up with the actuating device in at least one brake circuitvia a hydraulic connection. A simple master brake cylinder or a tandemmaster cylinder and an absolutely necessary pedal feel simulator can beprovided here.

The braking systems described above advantageously regulate in controloperation with a closed brake circuit, i.e., in control operation thereis no pressure reduction via solenoid valves in the reservoir, and/orthe pressure in the wheel brakes of the respective brake circuit iscontrolled or set using the PPC and/or multiplex method. To be on thesafe side, the switching valves should be connected to the wheel brakesin such a way that they open automatically when the wheel brake ispressurized. This advantageously ensures that the brake pressure in thewheel brakes can be reduced in any case and undesired braking or lockingof the wheels does not occur.

In an additional very advantageous design of the braking systemsdescribed above, at least one wheel brake, preferably two wheel brakes,is/are a hydraulically supported electromechanical brake (H-EMB), anelectric parking brake (EPB) or an electromechanical brake (EMB).Similarly, in addition to a conventional hydraulic wheel brake, anelectric motor of an additional electric parking brake or anelectromechanical brake can have a braking effect on the wheel. Thismeasure creates an additional redundancy. When a hydraulically supportedelectromechanical brake is provided, a braking force can advantageouslybe built up with this both hydraulically and electromechanically.

All modules are preferably controlled by a superordinate control unit(M-ECU) that is not located on the vehicle axle. Sends the controlsignals to the various actuators. It can thus control the pressuresupply devices, valves, electric drive motors and/or EMB or H-EMB duringthe braking process and/or ABS control operation and/or to diagnose thebraking system and, in addition to the brake, can also control othervehicle dynamics functions, e.g., steering, damping, roll stabilization,in a useful manner.

If at least one electric drive or traction motor is provided for atleast one axle or wheel of the vehicle, this can also be usedadvantageously for braking an axle or a wheel. This provides anadditional redundancy. In control operation or if a component of thebraking system, for example a pressure supply device, fails, a(supporting) braking force can also be produced by means of the tractionmotor(s). Through a combined use of pressure supply device(s),hydraulically supported electromechanical brake(s) H-EMB, electricparking brake(s) EPB and/or electromechanical brake(s) EMB and/or one ora plurality of drive motors(s), a faster increase in braking force witha shorter time-to-lock (TTL) or a higher braking torque canadvantageously take place in control operation or in the event offailure of one or a plurality of components of the braking system.

In the braking systems described above, each pressure supply device canadvantageously be preceded by at least one separating valve at theoutlet of the pressure supply, with the respective pressure supplydevice being able to be disconnected from the respective brake circuitby closing the separating valve, in particular if it fails.

In order to make the vehicle axle according to the invention with itsintegrated braking system even more secure against failure, at least onecontrol and regulating device of a pressure supply and valve assemblycan have a separate voltage supply and, in particular, signaltransmission, in particular all modules of a pressure supply device canbe supplied by at least two vehicle electrical systems and/or haveredundant signal transmissions. Two vehicle electrical systems meansthat either different voltage levels and/or voltage sources are used tosupply the components.

It is also advantageous if, in the aforementioned possible embodimentsof the braking system according to the invention, either the pressurecontrol in a brake circuit is carried out using at least one pressuresensor and/or via the current measurement of the motor current of thedrive and path control of the piston of the pressure supply device,which can be further refined in the pressure control quality by takinginto account the temperature of the drive. This enables precise pressurecontrol even without a pressure sensor, as has already been explained indetail in the patents on the PPC method (DE102005018649 B4 andDE102005055751B4 in function without a temperature sensor.

In order to enable safe separation of the brake circuits in the event ofa fault, e.g., a valve leak, and to reduce pressure in the wheel brakes,it is advantageous if a connection module with switching valves isarranged between the axles, so that either the brake circuits of thefront and rear axles connectable to one another, separable from oneanother and/or one or both brake circuits can be connected to thereservoir, in particular if no actuating device is provided via which apressure reduction in the reservoir can take place. The solenoid valvesthat are open in the de-energized state are advantageously used toconnect the brake circuits to the reservoir. For the connection betweenthe pressure units, de-energized closed solenoid valves or hydraulicfluid transfer pistons that can be locked in position should preferablybe used in the connection module.

The connection module can either have a plurality of solenoid valves,for example, via which a hydraulic connection can be established betweena brake circuit and the reservoir or between the two brake circuits.However, it is also possible that the connection module is formed by apiston-cylinder unit, the piston of which separates a first and a secondpressure chamber from one another, the first pressure chamber beingconnected to a first brake circuit and the second pressure chamber tothe other second brake circuit and the piston can be locked by means ofa blocking device. In the locked state, there would be virtually nohydraulic connection between the brake circuits, since a volume shift isprevented.

It is also advantageous if the piston-cylinder units of the vehicle axlehave redundant seals and hydraulic diagnostic lines and redundantcontrol and regulating units are also provided, and that the drives ofthe pressure supply devices have 2×3 phases, and that by means ofsensors of the motor current i_(phase), the motor angle a, in particularthe temperature T, is measured and taken into account in the pressurecontrol, and that there is in particular a redundant supply via twovehicle electrical systems or voltage levels, and in that redundantsignal transmission is provided. The provision of all these measuresadvantageously results in a very safe system which is suitable for ADlevels 3-5.

A reservoir can advantageously be used in the vehicle axles describedabove which has a plurality of separate chambers, one chamber of thereservoir being hydraulically connected or connectable to at least onepressure supply device and/or an additional chamber being hydraulicallyconnected or connectable to the connecting module. This advantageouslyresults in additional circuit options by means of the valves used, whichcontribute to the additional safety of the vehicle axle.

The above-described braking systems of the vehicle axles canadvantageously be operated in such a way that the deceleration of thewheels is carried out by means of the pressure supply device(s), theelectric drive motor(s) and the hydraulically supportedelectromechanical brake (H-EMB) at least for each axle, preferably foreach wheel or the electromechanical brake (EMB). Torque vectoring canalso be carried out by means of the pressure supply device(s), theelectric drive motor(s) (TM) and the hydraulically supportedelectromechanical brake (H-EMB) or the electromechanical brake (EMB).

When using a temperature sensor, the temperature of the drive of thepressure supply device(s) can also be determined and the temperature canbe used to more precisely determine the torque moment constant, whichdecreases linearly by the factor (1-Br %*ΔT) as a result of thetemperature increase of the rotor of the electric motor. This allows aneven more precise control of the torque and thus of the pressure, aslong as this is based on the relationship torque=kt(T) * phase currenti.

For pressure control, in addition to the current control, the pistonposition and the pressure volume characteristic can also be used and thechange in the pressure volume characteristic in the case of, e.g., airinclusion, can be adjusted by the pressure sensor or the H-EMB. Thecombined use of the two methods described above results in ahigh-precision pressure control that is also possible without a pressuresensor. This method provides additional redundancy in the event offailure of pressure transducers or can also be used to simplify thesystem with low redundancy requirements (e.g., system with only one orwithout pressure transducers).

The braking system of the vehicle axle according to the invention canalso be used for steering/torque vectoring and for actuatingtransmissions, in particular clutches, wherein the wheel-specificcontrol options with the at least one pressure supply and thehydraulically supported electromechanical brake(s) H-EMB, electricalparking brake(s) EPB and/or electromechanical brake(s) EMB and/or drivemotors or the steering EPS can be used.

The invention is thus characterized by a very simple structure with veryhigh availability, i.e., in the event of a complete or partial failureof modules, the function is not restricted or is restricted to a verysmall extent. Even if various components fail, almost maximumdeceleration and driving stability can always be ensured. For thispurpose, a deceleration of 0.6 to 0.9 g and an axle-based control orwheel-specific control with steering intervention/stability interventionis guaranteed even if a pressure supply device fails. A high level ofavailability and performance is thus achieved—once againcollectively—through the following measures, which can be providedindividually or in combination:

-   -   Mainly operation in the closed brake circuit (>90% of the        operating time) both in the brake booster (e-BKV), recuperation        operation and mainly in ABS control operation, thus avoiding        dormant faults. If the system is operated in an open manner, for        example in the ABS it is hydraulically connected to the        reservoir by opening a valve, which makes undetected leaks in        valves and seals (dormant faults) particularly difficult to        detect. Therefore, the operating state should be avoided or a        diagnosis of the tightness after every ABS operation is useful;        a diagnosis can take place in such a way that, for example, when        the valve is closed, the piston of the pressure supply is moved        and a volume loss or pressure increase is determined and        evaluated.    -   Redundancies and partial redundancies of the DV motor        electronics: e.g., design of the motor of the DV as a 2×3 phase        motor as well as partial redundancy of the motor control. This        means that if one of the electronic components fails (winding        short circuit, failure of a 3-phase line, the motor can still be        operated with half the torque. With a design for 200 bar, 100        bar, i.e., approximately the blocking pressure, can then also be        achieved in the event of failure. This means that even if one of        the electronics fails, ABS operation with maximum performance        with low coefficients of friction and satisfactory performance        in road conditions with a high coefficient of friction is        possible;    -   Partial redundancies of the electronics for the valve control.        If the electronics fail, it is very advantageous for        availability if the switching valves can still be operated.        Thus, redundancy for the valve control is to be provided in the        electronics so that the valve actuation still functions if the        engine control fails;    -   Use of an H-EMB, EMB or EPB in braking operation, in particular        use of EPB or H-EMB in the event of module failure. This means        that, on the one hand, the wheel can be braked via the hydraulic        access and via the electric motor built into the H-EMB. The        electric motor can be designed as an EC motor or a brush motor.        Thus, braking support can be provided by the electric motor on        the respective wheel;    -   Use of the used traction motors to increase the braking torque        with simultaneous recuperation of kinetic vehicle energy. Due to        the high inertia of the drive motor, however, it must be taken        into account that a braking torque can be built up less        dynamically via the traction motor than via the pressure supply        and the H-EMB, EPB or EMB;    -   Use of a fail-safe and diagnosable actuating unit with pedal        feel simulator, redundant displacement sensors and a        force-displacement sensor (KWS) as well as a special circuit for        diagnosing the pedal feel simulator;    -   Use of valves with a self-opening mechanism when there is        pressure in the wheel brake in such a way that the pressure in        the wheel brake opens the solenoid valve;    -   Use of a diagnosable connection module (VM) with which the brake        circuits can be safely connected or disconnected and the wheel        brakes can be connected to the reservoir, in particular if the        system does not have an actuating device (BE) with a connection        to the reservoir;    -   Use of a hydraulic fall-back level in a brake circuit or an axle        via connection of the actuating unit via a switching valve FV;    -   Subsequent delivery of volume of the DV when the volume limit is        reached;    -   Operation of the pressure position without pressure transducer        through intelligent, precise torque estimation from the motor        phase current, taking into account the motor temperature and the        pressure volume characteristic, which is compared via a pressure        transducer or the H-EMB function;    -   Use of trapezoidal spindle (no blocking of the spindle by dirt        particles in the raceway);

In Table 1 according to FIG. 7, the following are listed for the vehicleaxle according to the invention or various vehicle dynamics controlfunctions, such as electric brake boosting e-BKV, ABS operation,steering/torque vectoring, stability control/ESP, energy recovery byelectric motor and parking brake EPB, transmission lock GS, which can berepresented by the components pressure supply on axle 1 (DV1-A1 andDV2-A1) or pressure supply on axle 2 (DV-A2), TM1 and TM2 drive motors,electrohydraulic steering EPS and hydraulically supported H-EMB orparking brake EPB. Thus, the primary function and the secondaryfunction/redundancy are identified. This makes it clear that the mostimportant vehicle dynamics functions of an axle are available in atleast a double redundant manner. When designed as a 2×3 phase motor andconnection module between the front and rear axles, the pressure controlcan even be viewed as triple redundant.

The PPC method, see above for DE102005055751B4 and DE102005018649B4, canbe refined by temperature measurement and used for brakes, steering andclutches, in particular if the pressure transducer fails and forms anadditional redundancy in operation.

The e-axle system according to the invention with an integrated brakingsystem is therefore suitable for all levels of autonomous driving up tolevel 5 (AD).

A pressure supply device according to the invention can also be drivenby a rotary pump, which can in particular be a gear pump. It can thenhave a motor housing with an electric-motor drive arranged therein,which drives the gear pump. The drive has a stator and a rotor for thispurpose. An internal gear of the gear pump is moved via the rotor of thedrive. According to the invention, the drive is designed as a dry runnerby means of at least one seal, which is arranged between the rotor andthe inner gear wheel, or has a dry running rotor, i.e., the mediumconveyed by the gear pump does not flow around the rotor of the driveand/or is not surrounded by the medium. Due to the design as a dryrunner, the rotor rotates without major friction and flow resistance,which means that higher speeds and better efficiency can be achieved.

A particularly compact and simple pressure supply device is obtainedwhen the motor housing has a side wall on which the gear pump isarranged, in particular this has a recess in which the gear pump is atleast partially or entirely inserted. The side wall of the motor housingcan be penetrated by a shaft connected to the rotor in a rotationallyfixed manner, the gear wheel either being connected to the shaft in arotationally fixed manner or being coupled to the shaft via aninterposed gear and/or a clutch.

An advantageous compact and integrated design of the pressure supplydevice described above is obtained if the drive with its housing restsagainst a hydraulic housing with at least one valve and/or hydrauliclines or channels arranged therein or forms a unit therewith. The sidewall of the drive housing can abut or adjoin the side wall of thehydraulic housing, in particular be attached thereto, the particularlypot-shaped recess receiving the gear pump at least partially orcompletely and being open towards the hydraulic housing. With housingsarranged next to one another, the gear pump can either rest entirely inthe recess in the wall of the drive housing, entirely in a recess in thehydraulic housing or both in a recess in the side wall of the drivehousing and in a recess in the side wall of the hydraulic housing. Inthe latter case, the openings of the two recesses then face one another.Additional seals can be provided in order to seal the two housings toone another and to the outside.

The above-described recess in the side wall of the drive housing isadvantageously open to the outside and, if a hydraulic housing ispresent, opens thereto. The recess itself can advantageously be designedin the shape of a pot. It can also have a cylindrical section which iscircular in cross-section and in which the gear pump rests with itsgears.

The side wall of the drive housing can also advantageously be designedas a flange with which the drive can be fastened to another part orunit.

The gear pump used in the pressure supply device according to theinvention can be an internal gear pump with a sickle, an external gearpump or a toothed ring pump.

The gear pump can also advantageously be arranged axially next to thestator and/or the rotor of the drive, the structure and size thereof isnot disadvantageously limited by the gear pump. The size and structureof the gear pump is then not dependent on the dimensions of the statorand the rotor.

The drive housing can be designed in at least two parts, the side wallbeing part of or forming a first housing part. The second housing partcan, for example, be pot-shaped and accommodate the stator and the rotorof the drive.

As already stated, the rotor is connected to the gear by means of adrive shaft directly or via a transmission and/or a clutch. The gear canbe connected to the drive shaft in a rotationally fixed manner either bymeans of a force-fit connection or by means of a form-fit connection,which is formed in particular by means of a pin or serration. In thegear ring pump, the inner gear is arranged eccentrically on a partconnected to the drive shaft, in particular in the form of a disk or acam disk.

Both when the gear pump of the pressure supply device according to theinvention is designed as an internal gear pump or as a toothed ringpump, an external inner ring gear is also necessary in addition to theinternal gear. In the case of the internal gear pump, the inner ringgear is rotated about its axis of rotation by means of the internal gearwheel driven by the drive shaft, the inner gear wheel being arrangedeccentrically to the inner ring gear. The inner ring gear rotates in anouter ring or cylinder surrounding it. In addition, a sickle must beprovided which must be arranged in the space between the inner ring gearand the inner gear wheel resulting from the eccentricity.

In contrast to the internal gear pump, the inner ring gear is fixedlyarranged in the gear ring pump, the inner gear rolling, due to itseccentric mounting on the disc, being rotated by the drive shaft in theinner ring gear. A sickle as with the internal gear pump is notrequired.

According to the invention, the drive shaft can either be supported ormounted

-   -   a) in the motor housing, on the one hand, and in the gear pump        and/or in the hydraulic housing on the other hand, or    -   b) only in the gear pump or    -   c) in the hydraulic housing and in the motor housing or    -   d) in the gear pump and in the hydraulic housing        by means of suitable bearings, in particular radial bearings, in        the form of ball or roller bearings and/or axial bearings.

If a hydraulic housing is provided, the drive shaft can extend into thehydraulic housing, in particular up to its side opposite the drive. Forexample, a target for a sensor can be arranged on the drive shaft, thesensor being arranged in the control and regulating unit (ECU).Additional seals can prevent the delivered medium from entering thecontrol and regulating unit. It is also possible that the drive shaftextends right through the hydraulic housing and ends in the housingadjoining it, for example an control and regulating unit.

The gear pump can be designed differently as an internal gear pump.Thus, in a first embodiment, the inner gear, the inner ring gear, thesickle and the outer ring can be arranged between two disks, with thedisks being firmly connected to the outer ring after appropriatecentering and adjustment of the parts to one another. The cohesiveconnection can extend all the way around the circumference, resulting ina stable and compact embodiment in which the individual moving partshave only small clearances and gaps with one another, whereby goodefficiency is achieved and high pressure can be achieved.

Possible embodiments of the braking system according to the inventionare explained in more detail below with reference to drawings.

In the figures:

FIG. 1: shows a schematic representation of a first embodiment of thee-axle according to the invention with one or two redundant pressuresupply device(s) DV1-A1 (DV2-A2), an electric motor EM for driving anaxle, electrohydraulic power steering EHPS, electric parking brake andhydraulic control unit HCU as well as associated control electronics ofthe assembly;

FIG. 1a : shows a hydraulic principle circuit diagram of a firstembodiment of the e-axle according to FIG. 1 with an electric parkingbrake EPB and variant 1 of an electrohydraulic steering system EHPS witha pressure supply device;

FIG. 1b : shows a hydraulic principle circuit diagram of a secondpossible embodiment of the e-axle according to FIG. 1 with anelectromechanical brake EMB instead of an electric parking brake andredundant pressure supply device and variant 2 of an electrohydraulicsteering EHPS with a separate redundant pressure supply device;

FIG. 1c : shows a hydraulic principle circuit diagram of a secondpossible embodiment of the e-axle according to FIG. 1 with electricparking brake EPB and redundant pressure supply device for brakeactuation and separate redundant pressure supply device for steeringactuation;

FIG. 2: shows a schematic representation of a second embodiment of thee-axle according to the invention with a pressure supply device, ahydraulic control unit HCU, one drive motor per wheel and ahydraulically supported electric brake H-EMB and associated controlelectronics for the assemblies;

FIG. 2a : shows the hydraulic principle circuit diagram of the secondpossible embodiment of the e-axle according to FIG. 2;

FIG. 2b : shows a cross-sectional representation through a hydraulicallysupported electromechanical brake H-EMB for use in the second possibleembodiment

FIG. 3: shows a schematic representation of a third embodiment of thee-axle according to the invention with one or two pressure supplydevices, a hydraulic control unit HCU, an electric drive motor EM andmanual transmission SG with torque vectoring module TV and transmissionlock GS

FIG. 3a : shows a hydraulic principle circuit diagram of a first variantof the e-axle according to FIG. 3 with a redundant pressure supplydevice;

FIG. 3b : shows a hydraulic principle circuit diagram of a secondvariant of the e-axle according to FIG. 3 with a pressure supply deviceand actuating unit BE with hydraulic connection on axle 1 and connectionmodule VM to an additional pressure supply device on A2;

FIG. 3c : shows a hydraulic principle circuit diagram of a third variantof the e-axle according to FIG. 3 with a pressure supply device withhydraulic connection on axle 1 and connection module VM to an additionalpressure supply device on A2 and a central reservoir

FIG. 3d : shows the hydraulic principle circuit diagram of a fourthvariant of the e-axle according to FIG. 3, each with a pressure supplyunit for a wheel brake and a clutch of a dual clutch manualtransmission;

FIG. 3e : shows a hydraulic principle circuit diagram of a fifth variantof the e-axle according to FIG. 3 with a double stroke piston withredundant electronics for the actuation of wheel brakes and dualclutches;

FIG. 4: shows a pressure supply device with two control and regulatingdevices

FIG. 5: shows a pressure supply device designed as a double piston withtwo control and regulating devices, valve switching and redundant sealswith the possibility of diagnosing the failure of a seal

FIG. 6: shows a brake pressure control in the event of failure of thepressure transducer by means of current and temperature measurement andevaluation of the pressure-volume characteristic curve;

FIG. 7: Table 1: shows an e-axle primary function and secondaryfunction/redundancy;

FIG. 8a : shows a unit consisting of electric motor 22, single-circuitrotary pump Z, HCU with solenoid valves and ECU

FIG. 8b : shows a unit consisting of electric motor 22, two-circuitrotary pump Z, HCU with solenoid valves and ECU

FIG. 1 shows a first possible embodiment of the vehicle axle 100according to the invention with the wheels R1 and R2, each wheel beingbraked by means of a conventional wheel brake RB1, RB2 and additionallyhaving a parking brake EPB. The vehicle axle 100 also has an electricmotor EM with control EM-ECU to drive the axle, as well as anelectrohydraulic power steering EHPS. In a first design variant, thevehicle axle also has a pressure supply device DV1 which, together withthe valve assembly HCU, controls the pressure in the wheel brakes RB1and RB2 using the multiplex method and/or PPC method. The pressuresupply device DV1 is controlled by an control and regulating unit ECUDV1, which controls the electric drive motor of the pressure supplydevice DV1 by means of two separate phase systems, in particular 2×3phases. If one of the two phase or winding systems should fail, thedrive motor can still be operated with reduced power, so that there isnot a total failure of the pressure supply device DV1. If additionalredundancy is to be created, this can be done by providing a secondpressure supply device DV2, which is also controlled by an control andregulating device ECU DV2 and can also have two winding or phase systemsto increase reliability. The pressure supply or control of theelectrohydraulic power steering EHPS is also carried out by the pressuresupply device, this being done separately from the pressure control inthe wheel brakes by means of the valve assembly HCU. If supportedsteering is also required at the same time as the braking process, thewheel brakes RB1 and RB2 can be supplied together with the steering inmultiplex operation. If two pressure supply devices DV1 and DV2 areprovided, the steering system also has two redundant pressure supplydevices.

The dashed line marked 100 forms the system boundary of the vehicle axleaccording to the invention.

The valve assembly can be designed as shown in FIG. 1a , a switchingvalve SV1, SV2 being assigned to each wheel brake RB1, RB2. When theswitching valve SV1, SV2 is open, the pressure in the respective wheelbrake RB1, RB2 can be controlled by means of the pressure supply deviceV1, with the pressure in the respective wheel brake RB1, RB2 beingincluded or frozen when the switching valve SV1, SV2 is closed. It isoptionally possible to provide an outlet valve at least in one wheelbrake, so that the pressure in this wheel brake can be reduced via theoutlet valve. When the associated switching valve is closed, thepressure in the other wheel brake can then be built up at the same timeby means of the pressure supply device.

Should the pressure supply device fail in whole or in part, a brakingtorque can be produced alternatively or additionally with the parkingbrakes EPB and/or by means of the electric drive EM.

If an actuating device BE, not shown, is provided, as shownschematically in FIG. 1a , which has a piston-cylinder unit whose pistoncan be adjusted by means of the brake pedal of the actuating device BE,brake pressure can be built up in the wheel brakes RB1, RB2 in anemergency. In this case, the pressure supply device must be preceded bya separating valve TV1, which is closed without current, whereby thepressure supply device DV1 is separated from the wheel brakes RB1, RB2and the actuating device BE.

The pressure control in the wheel brakes takes place via the pressuretransducer p/U and additionally via the PPC method with position controlof the piston of the pressure supply device DV1, as well as additionallyor in the event of failure of the pressure transducer via the motorcurrent and pressure volume characteristic of the system. The pressurecontrol in the steering EHPS takes place via the volume control by wayof path control of the piston of the piston-cylinder unit of thesteering EHPS, for which the steering has at least one, advantageouslyan additional, preferably redundant, position sensor x/U, see FIG. 1a .The angle sensor can also be used as an alternative to the positionsensor a/U of the electric motor of the pressure supply device, which isalso designed redundantly.

All components of the vehicle axle are controlled by the superordinatecontrol and regulating unit M-ECU. Optionally, instead of an actuatingdevice BE, an electric brake pedal for brake-by-wire and an electricaccelerator pedal e-accelerator pedal can also be provided.

FIG. 1a shows a hydraulic diagram of the vehicle axle according to FIG.1 with only one pressure supply device DV1, this having two control andregulating units DV-ECU1 and DV-ECU2, each control and regulating unitcontrolling a 3-winding system of the drive so that even if a controlunit or a 3-winding system fails, the pressure supply can be operatedwith reduced dynamics and reduced maximum pressure.

The steering system EHPS has an inlet valve EVS1, EVS2, EVS3, EVS4 foreach pressure chamber, the piston for steering support being adjustableby opening the switching valves. The EHPS control follows in such a waythat the EVS1 valve and the EVS4 valve are opened to move the piston inthe direction of wheel R2, while EVS2 and EVS4 are closed. Whenadjusting in the direction of wheel R1, the EVS2 and EVS3 valve isopened and the EVS1, EVS4 valve is opened. If the valves leak, thesteering can be controlled using an emergency control method in such away that the leakage rates are determined via the piston of the pressuresupply device and the valves are intelligently controlled so thatsteering in both directions is possible despite the leakage. Foradditional redundancy, steering modules are provided on a plurality ofaxles.

FIG. 1b hows an additional embodiment for the vehicle axle according toFIG. 1a , a purely electrohydraulic brake being provided and thepressure supply device being connected only to the steering module. Incontrast to the steering system according to FIG. 1a , the steeringsystem EHPS has only one switching valve EVS1.

FIG. 1c shows an additional possible embodiment of the vehicle axleaccording to the invention, in which two pressure supply devices DV1 andDV2 are provided, each of which has two control and regulating unitsDV-ECU1 and DV-ECU2. Each control and regulating unit DV-ECU1 andDV-ECU2 controls its own phase or winding system of the motor M1, M2, sothat the control and regulating units are inherently redundant. Inaddition, additional redundancies can be provided if the voltage supplyand/or the signal lines for the control and regulating units DV-ECU1 andDV-ECU2 are designed to be redundant, i.e., a supply from two vehicleelectrical systems and/or two voltage levels BN1, BN2 is provided or thedata lines DS1, DS2 designed redundantly.

The pressure supply device DV1 is thus provided for pressure control inthe wheel brakes RB1 and RB2. The pressure supply device DV2 for thepressure control or pressure supply of the steering EHPS. The twohydraulic systems are separated from each other so that a fault in onesystem cannot affect the other. The functioning of the steering isdescribed in FIG. 1 a.

FIG. 2 shows a basic circuit diagram of a second possible embodiment ofthe vehicle axle 100. The wheel brakes RB1 and RB2 of the axle 100 areformed by hydraulically supported electromechanical brakes H-EMB, withwhich a braking force can be built up in control operation not only bymeans of the pressure supply device DV1 but also by means of its ownelectric drive. This can be used as a support or in the event of a totalfailure. In addition, the traction drives EM1 and EM2 can be used toproduce a deceleration of the vehicle wheels R1 and R2 either in asupporting manner or alone. The control and regulating unit ECU DV canbe designed identically to that in the previously described embodiments.In other words, it can be designed redundantly in itself. Optionally, asecond pressure supply device can also be provided as a replacement forthe pressure supply device DV1 in an emergency. The components arecontrolled by the superordinate control and regulating unit M-ECU, withan actuating unit BE optionally being provided, as already describedabove. This can either have a purely electronic brake pedal (e-brakepedal), or it has a piston-cylinder unit, the piston of which can beadjusted in an emergency to build up pressure in the wheel brakes usingthe brake pedal, so that emergency braking is still possible. Thisbraking force produced by the foot can be supported by the tractionmotors EM1, EM2 and the motors of the hydraulically supported brakesH-EMB.

Of course, a steering EHPS and/or clutch and gear selector can also beprovided on the axle in this embodiment, as will be described in thefollowing figures. Another pressure supply device (not shown) can alsobe provided, which is used for redundant pressure supply to the wheelbrakes H-EMB and/or for pressure supply to other components such as thesteering EHPS and/or clutch and gear actuators. The pressure supplydevices can also take over the supply of all components of the vehicleaxle in the event of a fault in a pressure supply device.

FIG. 2a shows the hydraulic lines and valves of the vehicle axle asshown and described in FIG. 2. In control operation, the de-energizedclosed separating valve TV is open, the pressure control in the wheelbrakes RB1, RB2 taking place in multiplex operation and/orsimultaneously by means of the pressure supply device DV1 and theswitching valves SV1, SV2. The pressure control can take place via thepressure measurement using the pressure transducer p/U. However, themotor current i of the motor M1 and the rotor position α and optionallythe temperature of the motor and the pressure-volume characteristiccurve can also be used in a supporting manner or in the event of afailure of the pressure transducer. In the event of a total failure ofthe pressure supply device DV1, the separating valve TV closes and thede-energized open separating valve TVBE opens, so that a pressure can bebuilt up in the wheel brakes by means of the actuating device BE.

FIG. 2b shows a cross-sectional view through a hydraulically supportedelectromechanical brake H-EMB, which can be connected to the pressuresupply device DV1 via a hydraulic connection HL-DV1, so that a force canbe applied to the brake disks either via the hydraulics and/or theelectric motor EM. The rotary movement of the electric motor istransferred into a linear movement via a gear G and produces the forceF_(EM) on the wheel brake. The transmission G is preferably designed tobe self-locking, so that the parking brake functions safely when thevehicle electrical system fails. In addition to the electric motor, ahydraulic force F_(hyd) is produced via the pressure supply. Dependingon the embodiment of the EM as a brush motor or a brushless motor withlower or higher power, the dynamics of the braking torque change and theadditionally available braking torque can be determined by the H-EMB byappropriate design of the components and matched to the hydraulic brake.

FIG. 3 shows an additional possible embodiment of a vehicle axleaccording to the invention, which has the following features:

-   -   Dual clutch transmission (in particular 2-speed for e-vehicles),    -   Additional torque vectoring module TVM, e.g., eTwinster-x        solution from GKN®, module integrated or separate in the 2-speed        transmission;    -   Torque vectoring can be solved technically in different ways; it        is also possible that the torque vectoring module TVM is part of        the manual transmission;    -   Transmission lock GS as an alternative to the parking brake;        this results in a redundancy through pressure supply with locked        pressure through closed switching valve SV (see hydraulic        parking brake—EP 2137427 A1), and additionally through electric        motor EM, which can be used for a certain time, since electric        vehicles have a very large battery capacity;    -   Manual transmission can also be AMT (PCT/EP2017/054643)

In the vehicle axle shown in FIG. 3, the pressure supply or controltakes place in the wheel brakes R1, R2 and the drive train: a) manualtransmission SG, b) torque vectoring TVM, transmission lock GS by meansof the pressure supply device DV1. Optionally, a second pressure supplydevice DV2 can be provided to increase the reliability of thecomponents.

The brake pedal and the e-accelerator pedal supply the input signals forthe superordinate control and regulating unit M-ECU. The valve assemblyHCU with the valves, not shown, controls the activation of theindividual components.

The brake pedal can be designed as a pure e-brake pedal and thus onlysupplies sensor signals. Optionally, it is also possible to provide anactuating device BE with a brake pedal and, for example, with a mastercylinder and hydraulic simulator, so that it is possible to establish ahydraulic connection to the HCU. This advantageously results in afall-back level in which the vehicle driver can produce brake pressurein the wheel brakes directly via the brake pedal, as has already beendescribed above.

The motor in the pressure supply device DV1 can be designed as a 6-phasemotor, two separate output stages, which each energize half the motorwindings being provided. This means that if an output stage ECU-DV1fails, 50% of the total engine power can still be provided.

The manual transmission SG can be actuated by means of two hydraulicallyoperated multi-plate clutches. However, other hydraulically actuatedswitching elements are also possible, such as hydr. actuated gearselector, hydr. activated freewheels, etc.

The electric motor EM advantageously communicates partly directly withthe control and regulating unit SG-ECU of the manual transmission SG.

Alternatively, a steering EHPS, as used in the embodiments describedabove, can also be provided for the vehicle axle according to FIG. 3.

FIG. 3a shows a possible embodiment in which the valves of the HCUaccording to FIG. 3 are shown. The de-energized open switching valvesSV1, SV2 are used, as already described, for controlling the pressure inthe wheel brakes. The pressure build-up and pressure decrease takesplace via the switching valve SV1, SV2, the pressure control for eachwheel taking place in multiplex operation (MUX).

The actuation of the clutches in the manual transmission SG takes placevia a preferably de-energized closed valve SGV1, SGSV2 for pressurebuild-up and a de-energized closed valve SGVA1, SGVA2 for pressurereduction. The pressure can optionally be controlled directly via thepressure supply unit DV1.

Alternatively, the pressure in the manual transmission SG can also becontrolled by high-frequency cycling of the valves SGV1, SGSV2, SGVA1and SGVA2. Two pressure transducers can be used to control the pressurein the manual transmission.

The torque vectoring HS-TV is actuated via the solenoid valve MV-TV. Theactuation of the transmission lock GS takes place via a valve SVGS,which is preferably closed when it is de-energized.

The brake pedal with path simulator WS can be connected to the hydrauliccircuit of the vehicle axle via the solenoid valve TVBE.

The pressure supply device DV1 can be separated from the othercomponents by means of the de-energized closed valve TV.

The redundancy of the motor control by means of the two control andregulating units DV-ECU1 and DV-ECU2 has already been explained indetail in the embodiments described above. Each sub-ECU controls threemotor phases and detects the signals of temperature T, phase current iand rotor anglea. If one sub-ECU fails, the other ECU can record allsignals and control the motor with approx. 50% overall performance,which is sufficient for the predominant and relevant braking maneuvers.

FIG. 3b shows a possible embodiment of a vehicle with two vehicle axlesA1 and A2 according to the invention, each of which is supplied by itsown pressure supply device DV1 and DV2. The axle A2 is not shown. Theconnection module VM enables the two hydraulic circuits of the two axlesA1 and A2 to be connected to one another. Thus, if one pressure supplydevice fails, the other still intact pressure supply device can takeover the pressure control for all components of the vehicle, whichresults in a high level of fault tolerance and redundancy. Theconnection module VM also enables a connection to the reservoir VB. Theinternal structure of the connection module is not shown in detail here.In a simple embodiment, however, it is possible for only three switchingvalves to be sufficient.

Additional hydraulically supported parking brakes H-EMB are installed onthe wheel brakes. Their function has already been described in detail inFIG. 2.

A reservoir VB supplies the pressure supply device DV1 with hydraulicfluid and it can be subsequently delivered. A VB2 with separate chambersK1 and K2 supplies the pressure supply device DV2 with hydraulic fluidand pressure can be released into the reservoir via the connectionmodule VM. In contrast to axle A1, a pressure release from the hydrauliccircuit of axle A2 is necessary because axle A2 does not have anactuating unit BE, which is typically designed hydraulically with aseparate reservoir (not shown). An overpressure in the hydraulic circuitof axle A1 can thus escape via the actuating unit BE. The actuating unitBE is connected to the hydraulic circuit of axle A1 via a de-energizedopen valve TVBE, so that if both pressure supply devices fail, a brakepressure can still be built up in the wheel brakes of axle A1.

The pressure supply and control of the manual transmission is describedin detail in FIG. 3a . In this respect, reference is made to thestatements made there. In contrast to FIG. 3a , a media separation MTKis optionally provided between the brake circuit and the transmissioncircuit. The optional media separating piston MTK enables a differentmedium to be used for actuating the transmission than for actuating thebrake. A separate reservoir VB3 must therefore be used, into which thevolume is drained when the clutch is activated. This reservoir is inturn connected to the MTK module.

Another difference between FIG. 3b and FIG. 3a is that an H-EMB is used.This mode of operation is described in detail in FIGS. 2a and 2b . Inaddition, additional hydraulic actuators for torque vectoring HS-TV areprovided, which are controlled via solenoid valve(s) MV-TV. The torquevectoring module HS-TV can be integrated in the transmission or designedseparately (see dashed line)

FIG. 3c shows an additional possible embodiment in which there is noactuating device BE. This corresponds to a vehicle structure with a pureelectric brake pedal for fully autonomous driving. Here the connectionmodule is designed in such a way that pressure can be released from thehydraulic circuits of both axles A1 and A2 into the reservoir VB. Inaddition, the pressure supplies DV1 and DV2 are connected to thereservoir VB, a separate chamber K2, K3 being assigned to each pressuresupply. Both pressure supplies can be subsequently delivered from thechambers K2 and K3 or, as an alternative, also be subsequently deliveredvia the VM module via the chamber K1. This creates an additionalredundancy and only one reservoir is required for all pressure supplies.

FIG. 3d shows an additional possible embodiment of a vehicle axle withtwo pressure supply units DV1 and DV2. One pressure supply device DV1,DV2 each controls a wheel brake RB1, RB2 and part of the manualtransmission actuator SG. The wheel brakes and manual transmissionactuations are connected to the respective pressure supply unit viasolenoid valves, which are preferably open when de-energized.Optionally, at least one media separating piston MTK can be installed sothat the brakes can be operated with a different hydraulic medium thanthe manual transmission SG. To actuate a wheel brake, the assignedswitching valve SV1, SV2 is opened and the valve of the assignedtransmission actuation is closed. To actuate the transmission SG, thevalve switching is reversed. Braking has priority over shifting themanual transmission SG.

Since switching is very seldom used on a vehicle axle, it can be assumedthat the pressure supply device is permanently connected to therespective wheel brake during the pressure modulation during braking.Shifting can take place during braking phases with constant pressure orafter braking.

The connection module VM enables the two hydraulic circuits to beconnected. A common reservoir VB with separate chambers K1, K2 and K3supplies the two pressure supply devices DV1 and DV2.

Although the system costs are higher compared to the embodimentaccording to FIG. 3b , the following advantages still outweigh thedisadvantages:

-   -   The two pressure supply devices DV1 and DV2 represent a total        redundancy without restrictions;    -   There are no restrictions in pressure control in the brake,        since multiplexing, i.e., supplying two wheel brakes with one        pressure supply device, is not necessary. The brake pressure can        be permanently controlled by the associated pressure supply        device DV1 or DV2 when the switching valve SV1 or SV2 is open;    -   If a pressure supply device DV1, DV2 fails, the connection        module VM makes it possible to operate both circuits with the        pressure supply device that is still functional. There are no        restrictions in the pressure level;    -   One switching valve is sufficient on each of the switching        elements in the manual transmission SG; no pressure transducers        are also required;    -   The actively adjustable volume in the pressure supply device can        be somewhat lower.

FIG. 3e shows an additional possible embodiment in which the pressuresupply device DV1 has a double stroke piston DHK, which is shown anddescribed in detail in FIG. 5. In contrast to the previous embodiment,each wheel brake has an outlet valve AV1 and AV2 with an optionalpressure transducer between the switching valve and the wheel brake.This has a number of advantages:

-   -   Thus, a pressure supply in both piston stroke movements is        possible, which means that an unlimited volume budget is        available and a shorter piston stroke is possible;    -   It is possible to connect the two hydraulic circuits, but also        to separate them;    -   Simultaneous pressure build-up and reduction possible in one        stroke direction, particularly advantageous for the simultaneous        actuation of the two clutches of a dual clutch transmission;    -   Motor downsizing is possible by connecting the two hydraulic        chambers of the double stroke piston and reducing the hydraulic        effective areas with an effect on the torque requirement of the        electric motor of the pressure supply device;    -   Closed circuits, i.e., the entire control of the brakes and        clutches takes place via the DHK unit and can therefore be        diagnosed very well    -   with no connection module VM necessary.    -   Dispensing with or reducing the size of the reservoir when        separating media, since little or no volume is lost in the        clutch    -   Pressure reduction via AV1, AV2 via PWM control with/without        pressure transducer or double-stroke piston pressure supply        system in the reservoir VB, thus additional degrees of freedom        in the pressure control of clutches and brakes

FIG. 3f shows an embodiment for a vehicle with two vehicle axles A1 andA2 according to the invention, the hydraulic circuits of which areconnected to one another via two hydraulic lines HL1 and HL2, each witha de-energized closed valve SVHL1, SVHL2. An electric motor EM, a manualtransmission SG, wheel brakes RB and torque vectoring HS-TV areinstalled on both axles A1 and A2. It is also possible to install onlywheel brakes on the axle A2. This results in the following advantages:

-   -   As a rule, the valves of a pressure supply device DV1, DV2 are        controlled by the ECU of the respective axle. However, if this        ECU fails, the connecting valve can no longer be activated. In        this embodiment there are two connecting valves SVHL1 and SVHL2,        which are each controlled via the associated ECU. This ensures        that the two hydraulic circuits can be connected even if an ECU        fails;    -   if only one pressure supply device DV1, DV2 fails, for example        due to a jammed spindle, but the associated ECU is still        functioning, both connecting valves can be opened so that the        total throttle losses are lower.

FIG. 4 shows a possible embodiment of a pressure supply device DV1 withtwo control and regulating devices DV-ECU1 and DV-ECU2. The pressuresupply device has an electric motor Ml, the rotor R of which adjusts aspindle SP which is connected to a piston KB. By adjusting the pistonKB, a pressure can be built up in the pressure chamber DR, which can bepassed into a brake circuit BK via the separating valve TV. The pistonis sealed by a plurality of seals in the cylinder, with a hydraulic lineleading to the reservoir between the seals. This means that the pressuresupply is still fully operational and redundant even if a seal fails.The pressure chamber DR is connected to the reservoir via a check valve.Thus, the pressure supply can subsequently deliver. Each of the twocontrol and regulating devices DV-ECU1 and DV-ECU2 are connected via 1×3phase lines with separate winding or phase systems of motor M1, so thatif one control and regulating device or winding system fails, motor M1still has the other winding or phase system and the other control andregulating device can be operated, even if only about half the torquecan then be produced by means of the drive Ml. One or both control andregulating device(s) has or have sensors for determining the temperatureT, the motor current i and the rotor angle α. To achieve a high level ofavailability, not only are the control and regulating devices DV-ECUredundant, but also power supplies BN1, BN2 and data and control linesDS1 and DS2 are provided twice. The power supplies BN1 and BN2 can, forexample, be different voltage levels of a vehicle electrical system orseparate vehicle electrical systems.

FIG. 5 shows a possible embodiment of a pressure supply device DVdesigned as a double-stroke piston with 2 pressure chambers anddifferent areas A1 and A2, the area ratio A1/A2 preferably being between1.5 and 2.5. The DV also has two control and regulating devices DV-ECU1and DV-ECU2. The pressure supply device has an electric motor Ml, therotor R of which adjusts a spindle SP which is connected to a piston KB.By adjusting the piston KB, a pressure can be built up in the pressurechamber DR, which can be passed into a brake circuit BK via theseparating valve TV. The piston is sealed by a plurality of seals in thecylinder, a redundant, diagnosable sealing system being created as withthe pressure supply device. In the pressure supply device, too, ahydraulic line leads to the reservoir between the seals. This means thatthe seals can be diagnosed and the pressure supply is still fullyoperational and redundant even if a seal fails. The pressure chambersDRx and DRx are connected to the reservoir via check valves and valvesxx and xx. This means that the pressure supply can draw volume from thereservoir in both pressure chambers Dxx and Dxx and a controlledpressure reduction is possible via both pressure chambers into thereservoir. The pressure reduction can take place via piston control orvalve control, e.g., by PWM pulsing of the valves. The pressuretransducers p/u are advantageously used for pressure control; the PPCregulation can additionally or alternatively be used. The two hydrauliccircuits HKI and HK II are connected via one or more bypass valve(s),which are preferably designed to be closed when de-energized. Thus, thepressure build-up in HK1 and HK2 can take place in the forward andbackward stroke directions. In addition, the effective area of thepiston in the forward and return stroke directions can be reducedbecause, when the bypass valve circuit is open, A1-A2 is effective inthe forward stroke direction and A2 in the return stroke direction. Inthis way, the torque requirement for the electric motor can be reducedand costs can be saved, and the load on the transmission can be reduceddue to lower axial forces. Each of the two control and regulatingdevices DV-ECU1 and DV-ECU2 are connected via 1×3 phase lines withseparate winding or phase systems of motor M1, so that if one controland regulating device or winding system fails, motor M1 still has theother winding or phase system and the other control and regulatingdevice can be operated, even if only about half the torque can then beproduced by means of the drive M1. One or both control and regulatingdevice(s) has or have sensors for determining the temperature T, themotor current i and the rotor angle α of the electric motor. To achievea high level of availability, not only are the control and regulatingdevices DV-ECU redundant, but also power supplies BN1, BN2 and data andcontrol lines DS1 and DS2 are provided twice. The power supplies BN1 andBN2 can, for example, be different voltage levels of a vehicleelectrical system or separate vehicle electrical systems.

FIG. 6 shows a brake pressure control in the event of a failure of thepressure transducer DG, with a control of the motor torque M_(Mot) andthus the control of the pressure p being carried out by measuring themotor current i_(phase) and evaluating the pressure-volumecharacteristic. The motor temperature T is also taken into account,since the torque constant is reduced under temperature and thus has aninfluence on the proportionality factor kt * (1-Br %*ΔT) between motortorque M_(Mot) and motor current i_(phase). This advantageously resultsin a redundancy of the pressure measurement. This also means that apressure transducer can be dispensed with. The control is calibrated bythe pressure transducer and it is primarily controlled with current,path and pressure volume characteristic.

Where

M _(mot) =kt*i _(phase)*(1−Br %*ΔT)

-   -   kt: torque constant    -   I_(phase): phase current    -   ΔT: temperature change in k    -   Br %: typical kt drop factor with increasing temperature

The PPC method (see introduction of DE102005055751B4 andDE102005018649B4) can be refined as a result and is used for brakes,steering, clutches, torque vectoring with clutch solution.

FIG. 8a shows a representation of an entire structural unit consistingof motor 22, pump Z, HCU and ECU, which is able to exercise pressurecontrol and control for systems such as brakes, transmissions, etc. Themain focus here is on the combination of motor and pump. The pump isarranged in the bearing flange 18 or attached to the HCU or ECU in aseparate pump housing 40, as shown in the upper half of the figure. InFIG. 8a a version is shown which requires an additional motor bearing 20in which the shaft 1 is mounted. As is usual, the motor is composed of arotor 21, which is connected to the shaft 1 via the driver 10 a . Therotor 21 is axially pretensioned by its force via a permanent magnet inthe housing 30. This is a solution for the motor manufacturer whomanufactures and tests the motor with housing 22 and stator and winding23 and delivers it to the system supplier. The motor is tested with anauxiliary shaft without a pump. Thereafter, when the shaft is removed,the rotor is centered by the axial magnetic force, so that the shaft 1can then be assembled with the rotor during final assembly. The drivehousing must also be joined and fastened here with the flange 18 at 25a—shown in the lower half of the figure—e.g., with springs, which areattached in segments over three connections. A housing seal 31 is alsonecessary here. It can be fastened by caulking, at 25 from the engineflange with HCU or ECU, see upper half of the FIG. 28. The pump versionwith pump housing is shown here. The motor is shown here as a brushlessmotor that needs a motor sensor for commutation and control of thevolume delivery of the pump. This motor sensor is arranged at a distancefrom the drive housing 22, a sensor shaft 26, which is arranged orattached to the drive shaft 1, carrying a sensor target 27. This target27 acts on the sensor element 28, which is arranged on the circuit boardof the ECU. The winding is connected to the ECU via contact bars 24.

The motor with bearing flange 18 can be connected directly to thehydraulic housing HCU, which includes valves or other hydr. componentsto be connected to the pump. If this is not the case, a connection ofthe drive housing 22, 18 directly to the housing of the ECU is possible.

It is also possible to arrange the gear pump Z in a pump housing 40which is connected directly to the hydraulic housing HCU, as is shown inFIG. 8a in the upper half of the drive shaft 1. Before the assembly ofthe pump housing 40 and the hydraulic housing HCU or the pump housing 40and the ECU, the gear pump Z is first integrated or mounted in the pumphousing 40, the rotor 21 then being pressed onto the shaft 1 and thenassembled with the bearing 20. Here, the tensile force of the magnet 30can also act on the rotor 21 and the bearing 20, so that the bearingacts like a four-point bearing. The motor housing 22 is thus connectedto the gear pump Z and its pump housing 40 and, in the next step, can beconnected to the hydraulic housing HCU or the electronics housing ECU.The fastening screw 41 is used for this. The shaft 1 is previouslycentered in the outer disks 7.1 and 7.2, so that the pump housing 40 iscentered with the shaft 1 before the screw connection to the hydraulichousing HCU or the electronics housing ECU.

The pressure supply device according to FIG. 8b uses a 2-stage pump witha long sliding or rolling bearing, which does not require a separatemotor bearing. Accordingly, the motor structure with the housing issimplified. The rotor 21 is seated with the driver 10 a on the motorshaft and is axially connected to the locking ring. The pump housingprotrudes slightly into the HCU here.

1. A vehicle axle having hydraulically operating wheel brakes and/or additional hydraulic loads, the vehicle axle including: at least one pressure supply device arranged to control pressure in the wheel brakes, wherein the at least one pressure supply device is driven by an electric-motor drive; at least one electronic control and regulating device and a valve assembly having values for setting wheel-specific brake pressures and/or for disconnecting the wheel brakes from or connecting the same to the at least one pressure supply device; at least one electric drive motor arranged to drive and brake a vehicle wheel or the vehicle axle, wherein the at least one pressure supply device is used to control pressure of and/or provide pressure to at least one additional brake unit in the form of a hydraulically supported electromechanical brake, a hydraulically operating steering device, a gear actuator and/or transmission actuator, and/or a torque vectoring module. 2.-37. (canceled) 